1. Field of the Invention
The present invention relates to a benzophenone compound and an ink composition that contains the same, and more particularly, to a benzophenone compound that improves the dispersibility and lightfastness of a colorant, and an ink composition that contains the benzophenone compound.
2. Description of the Related Art
In general, ink compositions for ink-jet printing contain a colorant, a solvent, and an additive such as a dispersing agent. A dye or a pigment may be used as the colorant. However, using a dye as the colorant is limited due to its poor waterfastness and lightfastness compared to a pigment.
One of common dispersing agents for such ink compositions is a polymeric dispersing agent that has both hydrophilic and hydrophobic groups. The hydrophobic group of the polymeric dispersing agent is responsible for the dispersibility of the colorant, whereas the hydrophilic group imparts steric stability to the colorant by interacting with an aqueous solvent.
However, the polymeric dispersing agent has a large molecular weight so that the physical properties, for example, the viscosity, of the ink composition are greatly affected even when there is a minor change in the amount of the polymeric dispersing agent. Accordingly, it is difficult to control the amount of the dispersing agent when preparing an ink composition. In addition, although the polymeric dispersing agent has hydrophilic groups in its molecular structure, the hydrophilic fraction in the polymeric compound is insufficient to allow the composition to fully dissolve in water, and a significant amount of time is required.
In general, a medium, such as paper, after printing with such an ink composition is exposed to moist air and/or sunlight, so that ink compositions that are effectively lightfast and waterfast are required.
As a method for improving the lightfastness of an ink composition, adding a large molecular weight silicon compound to the ink composition as a lightfast additive for a UV blocking effect was suggested (U.S. Pat. No. 6,346,595). However, the silicon compound has a complex structure and is less miscible with other components in the ink composition when it has a larger molecular weight. Furthermore, agglomeration and precipitation occur in the ink composition when it is stored for an extended period of time, failing to guarantee long-term storage stability.